INFLUENCE OF THE ANCIENT SUBDUCTION PROCESS ON THE ORICINE OF LATE COLLISION VOLCANISM IN THE LESSER CAUCASUS

Abstract

The article considers the petrogeochemical features of the Late Cenozoic collisional volcanism of the Lesser Caucasus. Based on new geochemical data, it is shown that Nb, Ta, Hf, and Zr minima are observed for basic and intermediate rocks. The salic rocks are strongly enriched in Rb, Ba, Th, La and depleted in Ti, Yb, Y relative to the primitive mantle. The enrichment in incompatible elements suggests that the source of the melt from which the magma was derived was a metasomatized lithospheric mantle enriched in potassium and incompatible elements. Late Miocene-Quaternary volcanics were formed at different degrees of melting of subduction-enriched subcontinental lithospheric mantle. The role of the suprasubduction material decreases during the evolution of volcanism over time due to an increase in the share of the asthenospheric component in the interval from the Upper Miocene to the Quaternary.